package org.apache.lucene.index;
/**
 * Copyright 2007 The Apache Software Foundation
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

import java.util.*;

/**
 * Store a sorted collection of {@link org.apache.lucene.index.TermVectorEntry}s.  Collects all term information
 * into a single, SortedSet.
 * <br/>
 * NOTE: This Mapper ignores all Field information for the Document.  This means that if you are using offset/positions you will not
 * know what Fields they correlate with.
 *  <br/>
 * This is not thread-safe  
 */
public class SortedTermVectorMapper extends TermVectorMapper {

    private SortedSet<TermVectorEntry> currentSet;
    private Map<String, TermVectorEntry> termToTVE = new HashMap<String, TermVectorEntry>();
    private boolean storeOffsets;
    private boolean storePositions;
    /**
     * Stand-in name for the field in {@link TermVectorEntry}.
     */
    public static final String ALL = "_ALL_";

    /**
     *
     * @param comparator A Comparator for sorting {@link TermVectorEntry}s
     */
    public SortedTermVectorMapper(Comparator<TermVectorEntry> comparator) {
        this(false, false, comparator);
    }

    public SortedTermVectorMapper(boolean ignoringPositions, boolean ignoringOffsets, Comparator<TermVectorEntry> comparator) {
        super(ignoringPositions, ignoringOffsets);
        currentSet = new TreeSet<TermVectorEntry>(comparator);
    }

    /**
     *
     * @param term The term to map
     * @param frequency The frequency of the term
     * @param offsets Offset information, may be null
     * @param positions Position information, may be null
     */
    //We need to combine any previous mentions of the term
    @Override
    public void map(String term, int frequency, TermVectorOffsetInfo[] offsets, int[] positions) {
        TermVectorEntry entry = termToTVE.get(term);
        if (entry == null) {
            entry = new TermVectorEntry(ALL, term, frequency, storeOffsets == true ? offsets : null, storePositions == true ? positions : null);
            termToTVE.put(term, entry);
            currentSet.add(entry);
        } else {
            entry.setFrequency(entry.getFrequency() + frequency);
            if (storeOffsets) {
                TermVectorOffsetInfo[] existingOffsets = entry.getOffsets();
                //A few diff. cases here:  offsets is null, existing offsets is null, both are null, same for positions
                if (existingOffsets != null && offsets != null && offsets.length > 0) {
                    //copy over the existing offsets
                    TermVectorOffsetInfo[] newOffsets = new TermVectorOffsetInfo[existingOffsets.length + offsets.length];
                    System.arraycopy(existingOffsets, 0, newOffsets, 0, existingOffsets.length);
                    System.arraycopy(offsets, 0, newOffsets, existingOffsets.length, offsets.length);
                    entry.setOffsets(newOffsets);
                } else if (existingOffsets == null && offsets != null && offsets.length > 0) {
                    entry.setOffsets(offsets);
                }
                //else leave it alone
            }
            if (storePositions) {
                int[] existingPositions = entry.getPositions();
                if (existingPositions != null && positions != null && positions.length > 0) {
                    int[] newPositions = new int[existingPositions.length + positions.length];
                    System.arraycopy(existingPositions, 0, newPositions, 0, existingPositions.length);
                    System.arraycopy(positions, 0, newPositions, existingPositions.length, positions.length);
                    entry.setPositions(newPositions);
                } else if (existingPositions == null && positions != null && positions.length > 0) {
                    entry.setPositions(positions);
                }
            }
        }

    }

    @Override
    public void setExpectations(String field, int numTerms, boolean storeOffsets, boolean storePositions) {

        this.storeOffsets = storeOffsets;
        this.storePositions = storePositions;
    }

    /**
     * The TermVectorEntrySet.  A SortedSet of {@link TermVectorEntry} objects.  Sort is by the comparator passed into the constructor.
     *<br/>
     * This set will be empty until after the mapping process takes place.
     *
     * @return The SortedSet of {@link TermVectorEntry}.
     */
    public SortedSet<TermVectorEntry> getTermVectorEntrySet() {
        return currentSet;
    }

}
